How long till Bing crosses Yahoo (or are they asymptotic)?
And when it does happen will anybody care? I know people who use Yahoo but I don't know any human on the planet that uses Bing.
Next time you're in a room with a group of people ask them 1) Have they have ever tried Bing, 2) If they have, do they continue to use Bing.
Based on my observation you may get 10% on the first question, but pretty universally you will get 0% on the second. In my observations about 60% have heard of Bing.